Side-tone eliminator for telephones



Dec. 28 1926. 1,611,948

w. o. REID SIDE TONE ELIMINATOR FOR TELEPHONEZS Filed Oct. 19, 1925 firm/0w Jib/f2] 2 61 5 1 3 ja w Patented Dec. 2?),

WALTER O. REID, OF lsIINNEAPGLIfl, ItZZlFlItIESOTA.

SIDE-TONE ELIMINATOEL FOR JJELEPEIONES.

Application filed October 19, 1925.

My invention has for its object to provide an extremely simple and lnq'hly our clent side tone eliminator for tele.

ones, and to this end it consists oi: the novel devices and combinations of devices hereinafter de scribed and defined in the claim.

As is well known, local noises entering the mouthpiece of the transmitter of a telephone pass directly through the instrument to the receiver where they are clearly audible to personusing the ins uncut, thus maxing it very diiiicult to hear a person talking at the other end of the line.

The invention, in its preferred form, is in the nature of an attachment for the mouthpiece of the transmitter ot a telephone and provides a yieldingly opened valve with a manually operated controller for operating said valve, at will, to close said mouthpiece.

In the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a fragmentary View, partly in side elevation and partly in section, of a portable telephone having the invention ap plied to the mouthpiece of its transmitter;

Fig. 2 is a view partly in plan and partly in section, taken on the line 22 of Fig. 1, on an enlarged scale; and

Fig. 3 is a view principally in longi tudinal central section of the invention removed trom the telephone with some parts broken away.

Of the parts of the telephone illustrated, it is important to note the stand 4:, transmitter 5 and its mouthpiece 6 having}: in its base 7 a plurality of sound passages 8.

The attachment, as illlustrated, includes a normally opened conically formed valve 9, arranged to be pressed onto the base 7 ot the mouthpiece 6 to close its sound passages 8. On the face of the valve 9 is a piece of felt 10 or other pliable material arranged for direct contact with the base 7 of he mouthpiece 6 to form a tight joint therewith when said valve is closed. Said valve 9 is provided with an axially extended stem 11 mounted in a tubular guide 12 secured to the under side of a holder 13 in the form of a spider, the arms of which span the mouthpiece 6 and rest on the rim thereof.

To detachably secure the holder 13 to the mouthpiece 6, the outer end portion 01" its arms are bent to form hook-like mem bore 14 arranged to be sprung; into interlocking engagement with the rim of said mouthpiece. @ne of the hook-like members is provided with an outturned finger see 15 by which it can be sprung out-ward release the holder 13 from the mouth- -ce 6. This same finger piece 15 is also arranged to engage the rim of the mouthpiece 6, after the other two hook-like members 14 have been interlocked therewith, and when pressure is applied thereto will be sprung; outward with a cam-action and snapped into interlocking engagement with said rim of the mouthpiece 6. 7

As one means of manually operating the valve 9, to press the same onto the base 7 and close the mouthpiece 6, one end of an endwise movable flexible cable 16, of twisted wire or the like, is attached to the outer end of the valve stem 11. Attached to the other or outer end of the cable 16 is a stem 17 which forms a rigid extension therefor and has on its outer end a thumbpiece 18 by which the cable 16 may be moved endwise. On the inner end of the stem 17 is a cylindrical body member 19 mounted in a rigid tubular casing 26 for axial sliding move ment,

A cap-like holder 21 is secured to the outer end of the casing 20 and is provided with an axial bore through which the stem 17 extends for endwise sliding movement. The inner end of the casing 20 is closed except for a passage for the cable 16. A coiled spring 22 encircling the cable 16 is compressed between the closed inner end of the casing 20 and the body member 19 and normally holds the stem 17 and its thumbpiece 18 projected to hold the valve 9 open by means of the cable 16. In the open position of the valve 9, the same engages the valve stem 'uide 12 as a stop.

To prevent the cable 16 from buckling when the thumb-piece 18 is depressed to close the valve 9, the same is mounted in a flexible tubing 28, the outer end portion at which surrounds the casing 20 and extends into the capping member of the holder 21. The inner end of the tubing: 23 is secured in acup-like member 26% detachably secured to the holder 13 by means of a stem having; internal screw-threaded engagement with the outer end portion of the valve stem guide 12. On the periphery of the member 24 is a knurled annular rib 2-6 by which-the stemf25 maybescrewed into or out: of; the valve stem guide 12.

When a person is talking over a telephone to which the side tone. eliminator is applied and Where there are side tones interfering with his hearing, he preferably holds, thecontroller for the yieldingly open valve 9 in the same hand in which. he is-zhol'ding:

The above: described attachment has, in actual usage, proveirhighly efficient: for the purpose had in View, and can be very quickly snapped. onto. 01: ofif. from the mouthpiece of ateleplione transmitter.

What Inclaimds:

A side tone eliminator attachment for telephones;having-a; mouthpiece with a perforated base comprising a spider-like holder applicable to the rim of-z'the mouthpiece and i having); a: valve stem. guide; as yieldingly open'efdl valve having at valve stem: mounted ll'l'SEtllZl guide, a-ncliasmanually'opemtedilflex ilile" controller. attached: tor the? stein:- off the valve and operative'to-projeetttheexvalve onto tlie base; 015 the: mouthpiece" for closingz said mouthpiece.

In testimony whereofsl; afiiic my signature.

VVAL'DERi @I- REID. 

